The present invention relates to a method for mounting drive train components of a hybrid drive according to the features disclosed in patent claim 1.
For some time now the trend has been to “hybridize” the conventional drives of vehicles. Many manufacturers offer vehicles with an automatic transmission optionally with or without a superposed “hybrid head.” For reasons relating to cost, the aim is to change or more specifically to replace as few components as possible in the process of hybridizing a “conventional drive train.”
The object of the invention is to provide a method for mounting drive train components of a hybrid drive. In this case the method can be carried out efficiently and takes into consideration that the individual members of the groups of components that are to be mounted or the individual members of the modules that are to be mounted are premounted by the various manufacturers and then delivered. The engineering objective is to make available drive-train components that are designed to optimize the assembly process.
This engineering object is achieved by means of the features disclosed in patent claim 1. Advantageous embodiments and further developments of the invention will be apparent from the dependent claims.
First of all, the invention is not restricted to a method, but rather also comprises the assembly-oriented (optimized) design of the individual components that are used in conjunction with the method.
The core components that are required to carry out the method according to the invention are an automatic transmission and the so-called hybrid head.
The term “automatic transmission” is to be interpreted very broadly. Basically it comprises any and all kinds of transmissions, wherein the ratios or more specifically the gears can be shifted in an electronically controlled manner. The term “automatic transmission” comprises, in particular, planetary-gear automatic transmissions with a plurality of infinitely variable transmission stages. In principle, however, it also comprises automated manual transmissions, wherein the driver can select the individual gear stages by means of a selector element, as well as infinitely variable gears.
Such an automatic transmission comprises a transmission casing and a transmission input shaft.
The term “hybrid head” is to be construed very loosely in the sense of a “torque superposition device” that has at least one first input, a second input and at least one output. The hybrid head has primarily or exclusively mechanical and hydraulic components. A first drive machine, which can be formed, for example, by means of an internal combustion engine, can be coupled with the first input. The rotor of an electric machine can be coupled with the second input of the hybrid head. The transmission input shaft of the automatic transmission can be coupled with the output. The hybrid head is a separate or more specifically autonomous module that is completely preassembled or more specifically can be completely preassembled. This separate module comprises a hybrid head casing, a first and a second drive element as well as an output element. The second drive element is also referred to below as a rotor drive element.
According to the invention, the hybrid head casing is first connected by flanges to the transmission casing of the automatic transmission. The concept “connected by flanges” means that the two casings are connected to each other, for example, by means of threaded connections. In this case the output element of the hybrid head is coupled in rotation with the transmission input shaft of the automatic transmission by means of a shaft-hub connection.
In an additional assembly step the electric machine, which can also be regarded as a separate unit, is installed in the hybrid head casing. In this case the stator of the electric machine is connected to the hybrid head casing; and the rotor is connected to the rotor drive element that forms the second drive element of the hybrid head.
According to the invention, the automatic transmission and/or the preassembled hybrid head and/or the electric machine and/or the hybrid head casing can be installed in an engine chamber by choice either “front/transversely” or “longitudinally.” The concept “front/transversely” means that a main rotational axis of the said components is arranged in essence transversely to the longitudinal direction of the vehicle. The concept “longitudinally” means that a main direction of rotation of the said components is arranged in essence parallel to a longitudinal direction of the vehicle.
The automatic transmission, the hybrid head and the electric machine are preferably separate, premounted components that are tested individually for their functionality prior to the “assembly.” Each of these components or at least some of these components can be supplied by different suppliers.
The automatic transmission can be filled with transmission oil as early as before the installation of the hybrid head. In particular, the automatic transmission can already be preassembled by the transmission manufacturer, tested and filled with transmission oil and then subsequently delivered to the vehicle manufacturer.
The automatic transmission can be closed oil-tight by means of a casing cover on the side facing the hybrid head. The casing cover can be fastened with screws to the rest of the transmission casing from the side of the hybrid head at the transmission manufacturer.
A central “interface” between the hybrid head and the automatic transmission is formed by means of the output element on the side of the hybrid head and by means of the transmission input shaft, which is to be coupled in rotation with the output element, on the side of the automatic transmission. It can be provided that the transmission input shaft protrudes from the transmission casing or more specifically from a corresponding opening of the casing cover of the automatic transmission.
In order to prevent the automatic transmission from being damaged or rather from fouling during the transport from the transmission manufacturer to the vehicle manufacturer, the automatic transmission can be delivered with a protective cover on the side of the transmission input shaft. The protective cover can be, for example, a protective cover, that is placed or screwed on the face side of the transmission casing.
In order to supply the individual lubricating points of the automatic transmission with lubricating oil, a mechanically driven transmission oil pump is provided. The mechanically driven transmission oil pump can be arranged inside the transmission casing and can be driven by means of a drive shaft, which projects from the transmission casing, in particular, from an opening of the transmission cover. The drive shaft for the mechanically driven oil pump can be formed by a hollow shaft, in which the transmission input shaft is arranged in a rotatable manner. The hollow shaft and the transmission input shaft can be arranged coaxially and can project from the transmission cover of the automatic transmission as the “drive interfaces” of the automatic transmission. Therefore, before or while the hybrid head is connected by flanges to the automatic transmission casing, an “oil pump drive” of the hybrid head is coupled in rotation with the drive shaft for the transmission oil pump. The oil pump drive of the hybrid head can be connected to or more specifically can be coupled, for example, with the drive shaft of the automatic transmission, which is provided for driving the mechanically driven transmission oil pump, by means of one or more flywheels.
In order to ensure a flawless alignment of the hybrid head in relation to the automatic transmission, the hybrid head casing can be centered radially in relation to the transmission casing by means of a centering collar.
In order to seal the hybrid head casing relative to the automatic transmission casing, a seal, which seals oil-tight, can be inserted between a front face of the hybrid head casing that faces the automatic transmission casing and a front face of the automatic transmission casing that faces the hybrid head casing. The seal may be, for example, a surface seal, for example, made of paper, an elastomer seal, a fluid seal, a molded rubber seal (in the bypass to a screw connection until it makes contact with the end stop) or any other oil sealing seal.
When the hybrid head casing is connected by flanges, the hybrid head casing can be fastened with screws to the transmission casing from the side of the hybrid head casing, so that the seal that is inserted between the two casings is compressed.
According to a further development of the invention, the hybrid head has not only the function of a torque superposition device, but also has a clutch, which is intended for and is suitable as a starter clutch. This clutch enables a startup from a stationary state and driven by one of the two “drive elements” or by both drive elements of the hybrid head. A hydraulic actuating unit can be provided in the hybrid head to actuate the starter clutch.
The starter clutch can be a multiple disk clutch that runs in an oil, in particular in the transmission oil of the automatic transmission. To the extent that the starter clutch is attached to the oil circuit of the automatic transmission, it can be provided that the starter clutch is supplied with transmission oil of the automatic transmission by way of an oil duct, which is provided in the transmission input shaft and which has one or more radially extending branch ducts.
According to a further development of the invention, the hybrid head has, furthermore, a torsional vibration damper, which is arranged in the hybrid head and which is supposed to minimize or more specifically to damp the torsional vibrations that are introduced into the transmission input shaft of the automatic transmission.
When the electric machine is installed in the hybrid head, it is necessary to make sure that the rotor of the electric machine is aligned exactly coaxially in relation to the stator. The invention proposes the use of a positioning element, which acts as a mounting aid and which positions the rotor exactly in relation to the stator when the electric machine is not yet installed. Then the “entire” electric machine can be installed in the hybrid head as a prefabricated and pretested module. Then the stator is connected, for example, screwed, to the hybrid head casing. The rotor is connected or more specifically fastened with screws to the rotor drive element. This arrangement ensures that the rotor stays positioned exactly in relation to the stator after the stator and the rotor have been installed and mounted. Once the stator and the rotor have been securely fastened by means of screws, the positioning element that is used as the mounting aid can be removed.
After the installation of the electric machine, an internal combustion engine-drive element of the hybrid head is coupled with a crankshaft of an internal combustion engine. The internal combustion engine-drive element is, as a general principle, a component that can be driven directly or indirectly by the internal combustion engine or more specifically a crankshaft of the internal combustion engine. According to the terminology used in the introductory part, the internal combustion engine-drive element corresponds to the first input of the hybrid head.
The hybrid head casing can be connected by flanges directly to the casing of the internal combustion engine or can be connected by flanges by means of a spacing element that has a shape similar to a ring. In order to compensate for the torsional vibrations of the crankshaft of the internal combustion engine, this crankshaft can be coupled with the internal combustion engine-drive element by means of a torsional vibration damper. To put it more precisely, an output element of the torsional vibration damper can be fastened with screws to the internal combustion engine-drive element of the hybrid head; and then a drive element of the torsional vibration damper can be coupled in rotation with the crankshaft. A starter gear ring, which interacts with a starter or more specifically a starter motor, can be fastened with screws to the drive element of the torsional vibration damper. The internal combustion engine can be started by means of the starter or more specifically the starter motor.
In order to be able to compensate for the relative movements of the drive element of the torsional vibration damper in the axial direction in relation to the crankshaft of the internal combustion engine when the drive element is in operation, the crankshaft can be connected to the drive element of the torsional vibration damper by means of an element (so-called “flexplate”) that is elastic in the axial direction of the crankshaft. The elastic element can be screwed together with the drive element of the torsional vibration damper by means of a plurality of screws that are arranged in such a way that they are distributed in the circumferential direction.
According to a further development of the invention, the screws are arranged obliquely in relation to the axial direction of the drive train or more specifically the crankshaft. These screws are screwed into the drive element of the torsional vibration damper preferably from the side of the internal combustion engine. In order to make it possible to tighten the screws, a mounting opening can be provided in the wall of the casing of the internal combustion engine. When the torsional vibration damper or rather the drive train is in suitable rotational positions, the individual screws can be tightened or loosened one after the other in succession by way of the mounting opening using a socket wrench.
Other objects, advantages and novel features of the present invention will become apparent from the following detailed description of one or more preferred embodiments when considered in conjunction with the accompanying drawings.